1. Field of the Invention
The present invention relates to an electronic musical instrument employing a musical tone signal forming apparatus which can be utilized for the music education system, music toys and the like.
2. Proir Art
Japanese Patent Laid-Open Publiclation No. 63-40199 discloses the conventional apparatus providing a non-linear conversion circuit within a signal circulating loop including a signal delay circuit. Herein, a waveform signal is circulating in the signal circulating loop, and the non-linear conversion circuit convolutes a start control signal from an exteranl device with the waveform signal. Thus, in response to the start control signal, this apparatus starts to form the waveform signal. Then, by repeatedly circulating the waveform signal through the signal circulating loop, the desirable musical tone waveform signal is to be formed.
The above-mentioned apparatus is suitable for simulating the wind instrument which generates the sounds by the reflecting and transmitting the air-flow which is blown into a resonance tube via a mouth-piece. However, the above-mentioned apparatus is not suitable for simulating the string bowing instrument such as the violin and viola to be played by bowing the strings.
Meanwhile, Japanese Patent Laid-Open Publication No. 63-40199 discloses a wave-guide type signal processor which carries out the operation process on waveform data inputted in the closed-loop including the delay circuit to thereby synthesize the musical tone or impart the special sound effect such as the reverberation to the musical tone.
This signal processor physically simulates the mechanical vibration system of the non-electronic instrument, such as the resonance tube of wind instrument and strings of stringed instrument, by use of the electric circuit. Therefore, it is expected that by inputting the non-linear signal corresponding to the motion of the reed or Embousure of wind instrument or the relative motion between the bow and string of the string bowing instrument into the above-mentioned closed loop, the sounds of the wind instrument and string bowing instrument can be simulated naturally with high-fidelity.
However, in the conventional electronic musical instrument using the non-linear musical tone synthesizing appararus which inputs the non-linear signal into the above-mentioned signal processor, it is difficult to control the synthesized sound in response to several kinds of performance parameters without overlooking nuances in the performance expression made by the non-electronic musical instrument because of the following reason.
Conventionally, the non-linear musical tone synthesizing apparatus uses one or more fixed non-linear tables as the non-linear signal generating source. Even if plural non-linear tables are used, one of them is selected by certain control variable, wherein one table is designed to generate one non-linear signal. Therefore, the kinds of non-linear signals must be limited by the number of tables to be provided, so that the selection of the non-linear signal must be narrowed. In other words, the electronic musical instrument using such non-linear musical tone synthesizing apparatus is restricted in its expression. For this reason, it is difficult to control the synthesized sound in response to several kinds of performance parameters without overlooking nuances in the performance expression made by the non-electronic musical instrument.